Why didn't they attack?

"I'm ready!" Nadia reported from the head of the formation.

"Same here!" Leila followed suit, reporting from the second line located right at the exit of the entryway.

"So am I," Daria joined the roll call, waving her hand at Mathew from behind Leila's back.

With one member down from their initial setup, Mathew could no longer deploy his group in the same, favorable formation. Yet, the benefits of doing so anyway were simply too great to pass on.

As such, rather than remodeling the entire thing to make the best use of everyone at once, Mathew opted to abandon the hopes of keeping the insides of the building perfectly safe.

With only Leila responsible for clearing out the zombies Mathew and Nadia would let through, she could easily get overwhelmed. And then, it would be all on Daria's shoulders to keep everyone safe by slaughtering all the zombies that would pass through the group.